1. Field of the Invention
The present invention relates to a water-dispersed pressure-sensitive adhesive (PSA) composition comprising an acrylic copolymer as a base polymer, and a PSA sheet using the same.
The present application claims priority based on Japanese Patent Application No. 2008-267299 filed on 16 Oct. 2008, and the entirety thereof is incorporated herein by reference.
2. Description of the Related Art
Acrylic water-dispersed (aqueous) pressure-sensitive compositions comprising an acrylic polymer dispersed in water make use of water as a dispersion medium, and therefore they are preferable to solvent type PSA compositions from the standpoint of protecting the environment. Thus, an acrylic, aqueous pressure-sensitive PSA composition capable of forming a PSA sheet that provides a higher level of performance is in demand for reducing the use of organic solvents. Because of its ease in handling, a double-sided PSA sheet (typically a tape) wherein a PSA layer is formed on both sides of a substrate such as nonwoven fabric, etc., is widely used not only for bonding and laminating paper, synthetic resin films, etc., but also as a bonding means with good working properties and a high level of adhesive reliability in a variety of industrial fields ranging from household appliances to automobiles, various types of machinery, electric and electronic devices, nameplates and labels, etc. Therefore, it will be useful to provide an acrylic aqueous pressure-sensitive PSA composition that can be formed into a double-sided PSA sheet that provides excellent performance in these applications.
Examples of prior art documents relating to acrylic PSAs include Japanese Patent Application Laid-open Nos. 2002-167557, 2002-294209, 2001-335767, H10-279907, H8-209086, 2000-265140, 2003-193006, H8-218040, H8-333550, H11-241053, 2001-107007, and 2006-56936.